Authorities were determining Friday whether a black man found hanging from a tree in southwest Mississippi was a case of murder or suicide.

Otis Byrd, 54, was identified by authorities at a Friday afternoon press conference. He was discovered in Port Gibson Thursday morning, near the Louisiana border, after vanishing earlier this month. Thirty federal, state and local investigators are involved in the investigation.

"We're trying to determine the cause of his death, wherever that takes us," Don Alway, the FBI special agent in charge of the investigation, told reporters.

Alway added that authorities were still trying to find out more details about Byrd's life, both personal and professional. Claiborne County Sheriff Marvin Lucas said Thursday night that Byrd was convicted in 1980 for the murder of a woman, and served about 30 years in prison before being released about two years ago. His body was decomposing when found, and he was hanging from the tree with a sheet for about two weeks, Lucas said Thursday.

Alway would not discuss specifics about the investigation Friday, but said he had no information that suggested a firearm was used in Byrd's death.

A preliminary report on the cause of Byrd's death is expected early next week.

FoxNews.com's Karl de Vries and The Associated Press contributed to this report.